Drug interactions
Diazepam intranasal + Isoniazid
Severity: Moderate
Diazepam intranasal and Isoniazid: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Isoniazid inhibits CYP2C19 and CYP3A4, the main enzymes eliminating diazepam and its active metabolite. This can prolong diazepam effects, causing excess sedation and respiratory depression.
What this interaction means in plain words
Diazepam intranasal and Isoniazid can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Inhibition of CYP2C19 and CYP3A4 by isoniazid reduces diazepam clearance.
What to do
Monitor for excessive sedation and respiratory depression, particularly with repeated doses. Consider a lower diazepam dose or longer dosing interval.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Isoniazid
Frequently asked questions
Can I take Diazepam intranasal with Isoniazid?
MediHelp rates the interaction as moderate. Diazepam intranasal and Isoniazid can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Isoniazid inhibits CYP2C19 and CYP3A4, the main enzymes eliminating diazepam and its active metabolite. This can prolong diazepam effects, causing excess sedation and respiratory depression.
How serious is the interaction between Diazepam intranasal and Isoniazid?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for excessive sedation and respiratory depression, particularly with repeated doses. Consider a lower diazepam dose or longer dosing interval.
What other medicines interact with Isoniazid?
MediHelp also lists interactions of Isoniazid with, for example, Bacillus calmette-guerin substrain tice, Benzhydrocodone / acetaminophen, Carbamazepine. The full list is on the Isoniazid page.
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